1. Field of the Invention
A virbratory earth penetrator employing high pressure air controlled by an air distributor mechanism and synchronized with an eccentric mechanical oscillator is employed to gently penetrate soil without damaging the underground utilities with which it comes into contact.
2. Description of the Prior Art
The prior art literature reveals a number of patents which employ compressed gases, such as high pressure air, to assist in the digging of a hole. For example, U.S. Pat. No. 3,916,634 discloses an apparatus for digging holes in rather soft, sandy soil by forcing compressed air down an annular sleeve, thereby causing the soil at the bottom of the sleeve to be eroded and forced up and out of an inner passageway. U.S. Pat. No. 3,825,082 is a divisional of U.S. Pat. No. 3,916,634 and is therefore relevant for the same reasons. The following patents were cited in the prosecution of U.S. Pat. No. 3,916,634 and therefore may have relevance of their own: U.S. Pat. Nos. 1,173,355; 1,762,012; 1,853,397; 2,019,719; 2,786,652; 3,020,965; 3,274,782 and 3,674,100. Of the foregoing group U.S. Pat. No. 2,786,652 is notable in that it discusses the use of pressurized gas to erode material at the bottom of a pipe string. The drill includes a mechanism which causes it to rotate in a conventional fashion and a means for controlling the pressure of the gas at the bottom of the well bore. U.S. Pat. No. 1,762,012 discloses the use of compressed air to dislodge materials at the bottom of a well. Also, U.S. Pat. No. 3,674,100 discloses a combined compressed air and water drilling apparatus. Lastly, U.S. Pat. No. 2,019,719 discloses a "Terrestial Excavation" device that employs both air and water as eroding fluids. A plurality of orifices located at regular intervals around the periphery of the bottom of the drill bit act to improve the operation of the overall device. The other patents cited in U.S. Pat. No. 3,916,634 appear to be significantly less relevant.
U.S. Pat. No. 3,419,092 discloses a "Well Drilling Method" which does not necessarily require a rotating drill or bit, but instead employs air or other gas to assist in drilling operations at off-shore locations. Similarly, U.S. Pat. No. 3,851,490 discloses the use of a combination of air and water to drill a hole for setting a pile. U.S. Pat. No. 2,167,393 discloses another process in which a combination of a fluid and liquid can be used to improve the efficiency of a drill.
A number of prior art patents disclose the use of a liquid, such as water for erosion purposes rather than air. For example, U.S. Pat. No. 3,638,741 discloses an hydraulic "Post Hole Borer". Similar devices using water or similar liquids for drilling holes are described in U.S. Pat. Nos. 118,369; 789,324; 1,659,826; 2,605,090 and 3,938,600.
U.S. Pat. No. 3,920,090 is notable for its disclosure of a "Control Method and Apparatus for Pressure, Vacuum or Pressure-Vacuum Circulation in Drilling System". That patent discloses the use of compressed air and vacuum to remove earth at the bottom of a well hole, and also discloses the use of a device to apply upward tension on the drill.
The prior art also discloses isolated instances of the use of a vibrating mechanism to assist with an earth penetrator. For example, U.S. Pat. No. 2,743,585 describes a variety of methods for inducing vibrations in piles by means of unbalanced weights.
U.S Pat. No. 4,266,619 is of interest in that it describes a "Down Hole Cycloidal Drill Drive" which causes the drill bit at the end of a bore hole to precess. An eccentric weight causes a portion of the drill and stem assembly to precess or roll against the wall of the bore hole in a cycloidal manner and in forceable engagement with the bore hole wall to cause rotation of the drill stem about its own axis. U.S. Pat. No. 3,212,344 describes an "Apparatus Producing Oscillatory Movement of a Shaft" which includes two out-of-balance weights rotating in opposite directions with respect to each other. U.S. Pat. No. 2,229,912 describes a "Method and Apparatus for Displacing Penetrable Material" which comprehends the use of a captive "out-of-balance" weight for producing oscillations. Similarly, a number of patents discuss a method referred to as "Sonic" drilling. See for example, U.S. Pat. Nos. 3,256,789 and 3,360,056. According to another technique, oscillations may be set up along the entire length of the pipe string causing the string to oscillate as a whole. See for example, the eccentric orbiting elongated mass described in U.S. Pat. No. 4,271,915. Also, note the use of an elongated oscillatorv device is described in U.S. Pat. No. 3,049,185.
The prior art further discloses some devices in which the vibration of a drilling element is related to the use of the application of air or other materials. Note, for example, U.S. Pat. No. 3,076,513 that discloses a device including an eccentric drive mechanism that helps settle a bit into a hole. In addition, means are provided for forcing fluid into the hole through orifices. Similarly, U.S. Pat. No. 2,340,959 discloses a "vibrating mechanism" and the use of "acids and oils" for the purpose of assisting in the drilling operation. U.S. Pat. No. 2,360,803 discloses the use of an eccentric weight in the context of a drill that employs a liquid or paste to expedite the drilling process. U.S. Pat. No. 3,280,925 discloses the use of air or water in the context of a percussive drilling device. Similarly, U.S. Pat. No. 3,292,719 discloses a "Drill Bit" equipped with roller cutters which also uses a liquid or gas to expedite the drilling process. Also, U.S. Pat. No. 3,416,617 discloses the use of roller bits and circulating fluid to help erode and remove the soil from the bottom of a well.
Lastly, there appear to be a number of prior art patents related to automatic tensioning devices. Several of those are found in the context of off-shore, floating well drilling platforms. Note for example, U.S. Pat. No. 4,268,013 entitled "Crane Motion Compensator" in which a mechanism is described including a master pressure cylinder which is automatically controlled to displace a sheave to keep a constant displacement between a crane and a loading dock. U.S. Pat. No. 3,891,038 discloses a similar device including a piston and two pulleys. U.S. Pat. No. 3,151,686 discloses a "Hydraulic Weight Control and Compensating Apparatus" which includes a piston and a pair of pulleys designed to maintain a constant tension on a drill string. The structure disclosed in U.S. Pat. No. 3,158,206 is similar to that in U.S. Pat. No. 3,151,686 and further includes an unusual sensor mechanism to control the flow of hydraulic fluid to a master cylinder. U.S. Pat. No. 4,272,059 entitled "Riser Tensioner System" employs a pair of cylinders each having an individual sheave associated therewith. Lastly, U.S. Pat. No. 1,935,105 discloses another tensioning mechanism in which a hydraulic cylinder controls the tension exerted on a drill bit.
Insofar as understood, none of the prior art described above teaches or suggests a penetrating device in which the discharge of compressed gases is synchronized with an oscillating mechanism to improve penetrability. Moreover, the combination of air and oscillation with this invention's special tensioning mechanism appears to be novel in the context of prior art devices.